1. Field of the Invention
The present invention relates to a stabilizer, a method of manufacturing the same, a thermoplastic polymer composition using the stabilizer, and a method of stabilizing a thermoplastic polymer.
2. Description of the Background Art
In order to improve physical properties such as process stability, elasticity, adhesiveness, impact resistance, coloring resistance, and heat resistance of a thermoplastic polymer such as polypropylene and polystyrene, a bisphenol monoester represented by the following Formula (1):
wherein each R1 and R2 independently represents an alkyl group having 1 to 5 carbon atoms, R3 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R4 represents a hydrogen atom or a methyl group, has been compounded as a stabilizer (for example, refer to Japanese Patent Laying-Open No. 01-168643 (Patent Document 1) and Japanese Patent Laying-Open No. 03-88841 (Patent Document 2)).
In general, since there is a possibility that existence of a small amount of impurities in a stabilizer adversely affects stabilization performance including process stability, a stabilizer that is purified at a high purity so that impurities are not contained is available commercially and used. For example, a bisphenol monoester that is purified so as to be almost completely pure using a purification method disclosed in Japanese Patent Laying-Open No. 04-327558 (Patent Document 3) is available commercially and used as a stabilizer.